Separation of asphalt-type bituminous materials with acetone



Unite States atent 3,003,945 SEPARATION OF ASPHALT-TYPE BITUMINOUSMATERIALS WITH ACETONE Leo Garwin, Oklahoma City, Okla, assignor toKerr- McGee Oil Industries, Inc., a corporation of Delaware No Drawing.Continuation of application Ser. No. 435,351, June 8, 1954. Thisapplication Nov. 5, 1958, Ser. No. 771,963

8 Claims. (Cl. 208- --45) The present invention relates to a process forseparating an asphalt-type bituminous material into two or morefractions. More particularly, the present invention relates to animproved process for separating an asphalt-type bituminous material intoat least two fractions at a greatly improved rate of separation by useof a selective solvent.

This application is a continuation of my copending application SerialNumber 435,351, filed June 8, 1954, now abandoned.

By the term asphalt-type bituminous material as used in thisspecification including the claims is meant bituminous residues obtainedby refining hydrocarbons (crudes) naturally occurring asphalts (bitumensand pyrobitumens) one or more fractions or components thereof, orproducts obtained by blowing these materials or one or more of theircomponents or fractions with air or another oxygencontaining gas in thepresence or absence of catalysts. Examples of naturally occurringasphalts include gilsonite, grahamite, wurtzilite, albertite, elaterite,native asphalts, such as Trinidad asphalt, etc. Blown asphalt-typebituminous materials include those blown either in the presence orabsence of catalysts such as phosphorous pentoxide,

ferric chloride, cobaltio salts, etc. By the term one or more fractionsor components thereof is meant an asphalt-type bituminous material fromwhich a portion or the total asphaltene content has been removed, for example, by the method described in copending application Serial Number218,480, filed March 30, 1951, or an asphalt-type bituminous materialfrom which the asphaltenes as well as a portion of the resin content hasbeen removed by, for example, the same method.

Since asphalt type bituminous materials are highly complex mixtures of avery large number of compounds covering a wide range of structures andmolecular weights, it is customary to characterize their composition bysolubility in definite amounts of arbitrarily selected solvents. Thuswhen, for example, such a material is thoroughly mixed at roomtemperature with a parafiin hydrocarbon solvent containing fromfour toeight carbon atoms, inclusive, and certain other solvents, theundissolved portion settling out as solids is classified ordinarily asasphaltenes and the soluble portion as a mixture of resins and oils oras petrolenes. Since the amount of material that settles out variessomewhat with each of these solvents, the undissolved portion issometimes more specifically designated as normal peutane asphaltenes,isopentane asphaltenes, etc.

As a rule, the average molecular weight and structural complexityincrease from the oily to the resinous fraction and finally to theundissolved fraction or asphaltenes. Generally, these three fractions orcategories differ in their physical and chemical behavior. However, itis believed that there are individual members of each group which areborderline cases and which may fall into one fraction or category oranother depending upon the treatment used, e.g,, the kind and amount ofsolvent. Hence, from the foregoing discussion of the nature ofasphalt-type bituminous materials, it will be appreciated that the termsasphaltenes, resins and oils, as applied to asphalttype bituminousmaterials refer to broad classes or categories of the consti uents ofasphalt-type bituminous materials, the exact composition being dependentupon the particular asphalt-type bituminous material from which theywere derived, the agents, such as solvents, employed for separatingthese fractions from each other, the conditions including solvent volumeand temperature employed for carrying out the separation, and a numberof other factors. Nevertheless, these terms provide a convenient meansfor those skilled in the art to refer to broad classes of theconstituents of asphalt-type bituminous materials which do possessvaried chemical and physical properties even though, for example, anasphaltene may contain some constituents which are the same as thoseoccurring in the resins.

Each of the fractions or categories into which asphalttype bituminousmaterials may be separated is useful for purposes for which the parentmaterial is not suitable or when used for the same purpose, givesresults which are new and useful. Thus, when the parent material issteam or vacuum-reduced asphalt, the oils have lubricating properties,the resins are useful in coating compositions and as extenders inplastics manufacture and the asphaltenes are useful as rubber extendersand in coating compositions. Also, the resins, oils and asphaltenes maybe used singly or in combination as additives to modify the propertiesof asphalt-type bituminous materials.

Copending application Serial Number 218,480, filed March 30, 1951, nowUS. Patent No. 2,783,188 describes a method of separating asphalt-typebituminous materials into three fractions or categories, namely, theasphaltenes, the resins and the oils. In accordance with this method,the asphaltenes are separated from the resin-oil mixture or petrolenecontent by treating the asphalt charge with normal pentane or a similarsolvent under ambientlternperature conditions and allowing theasphaltenes to'set-tle out. Asphaltenes separated in this manner settleout very slowly due to the flocculent nature of the asphal-teneparticles. Asphaltene floc is very light and coarse and consequently theasphaltenes settle out only when several small fioc particles combinethrough physical contact to form a larger particle. Asp-haltenes fromblown asphalts are particularly difiicult to handle. They frequentlysettle out at one-tenth or one-twentieth of the rate exhibited byasphaltenes from vacuum-reduced asphalts. Many attempts have been madeto improve the settling rate of the asphaltenes. All of these attemptshave resulted in methods possessing notable disadvantages. The moreimportant methods used to improve the settling rate of asphaltenes and adiscussion of the disadvantages of these meth-v ods may be summarized asfollows:

(a) Centrifuging of the asphaltene suspension is satisfactory insofar asthe physioal separation obtained is con cerned. However, the equipmentin which the centrifuging is carried out is quite costly and theoperating charges 1 are high.

(b) Filtration methods have not been too successful. Due to thecompressible nature of the flue, the pressure under which filtration maybe carried out must be low to avoid compaction and plugging of thefilter. The over-all filtration rate is consequently low. Filter aidshave been used, both as precoats and as part of the mixture, to increasethe filtration rate. Improvement of the filtration rate has beenachieved by this, but the addition of a filter aid increases the costand creates a subsequent problem of removing the filter aid from thefinished asphaltene product.

(c) Gravity settling has a number of disadvantages and because of thelow settling rate under ordinary con ditions of temperature andpressure, expensive thickeners are required. The selling rate can beimproved significantly by raising the temperature of settling, the uppertemperature limit being the boiling point of'the ervant; Even below theboiling point, convection currents may. be serious. Furthermore, shouldthe settled solid fio-c be 3 allowed by accident or plant shut-down tostand in the settler without agitation and removal, it would compact andthe degree of compaction would be so great that after a twenty-four hourperiod it would be necessary to remove the solids by hand or bymechanical means.

Another serious disadvantage connected with the conventional separationof asphaltenes in the gravity settler results from the fact theasphaltenes cannot be removed continuously from the bottom of thethickener in dry form. It is necessary to incorporate enough liquid toprovide the necessary fluidity for pumpability. In most cases, at leastone or two volumes of liquid are required per volume of solid to give apumpable slurry. Under such conditions, contamination of the asphaltenefraction by the resins and oils dissolved in the liquid removed alongwith the solid is inevitable. Multiple-countercurrent thickening andwashing would eliminate this, but the cost is practically prohibitive.

The separation of the petrolene fraction into separate resin and oilfractions also poses difficult problems. For example, in the percolationprocess described in copending application Serial Number 218,480, filedMarch 30, 1951, the separation of the resin-oil mixture in hydrocarbonsolvent involves contact with a moving bed adsorbent such as clay,alumina, etc. The resins are preferentially adsorbed. The claycontaining the adsorbed resins must in turn be treated with an eluant toremove the resins from the clay and to allow the clay to be recycledinto the system. The resins as produced in this manner have a softeningpoint in the neighborhood of 170 to 180 F. and a penetration at 77 F. ofl-2. Thus, the characteristics of the resin fraction and its yield arefairly definitely fixed. There is not much in the way of latitude ofoperation to produce a variety of resin fractions of different physicalcharacteristics. Further, it is necessary that the eluant be removedfrom the resin, usually by distillation, in order that it may berecycled in the system. The percolation process as operated in thisfashion is expensive because it requires large quantities of circulatingclay, expensive mechanical equipment for moving the clay from one partof the system to the other and appreciable clay make-up because ofattrition of the clay particles and decreasing capacity of the clay forresin as it is used over and over again. In addition, this processbrings about attendant problems due to erosion of the steel equipment bythe moving clay particles, involves difiiculty in control because of theneed to measure the amount of clay circulation, and involves specialdesign of clay contactors to prevent bridging and loss of circulation ofthe clay. There are, to be sure, other processm for separating theresins and oils from each other. However, these processes involvedifiiculties equally as great, if not greater, than those set forthabove in connection with the percolation process.

Accordingly, it is a principal object of the present invention toprovide an improved method for separating an asphalt-type material intoat least two fractions.

It is a further object of the present invention to provide an improvedmethod for separating the asphaltene fraction or a portion thereof froman asphalt-type material in a manner which eliminates the difficultiesof low settling rate obtained when separating asphaltenes in theconventional manner.

-A further object of the present invention is to provide an improvedmethod for separating the asphaltene fraction or a portion thereof froman asphalt-type material in a manner permitting continuous operation tobe used instead of the usual batch process techniques.

A further object of the present invention is to provide a method forseparating the petrolene fraction of an asphalt type material into atleast two fractions, one of which contains the resins and the other ofwhich contains the oils.

Another object of the present invention is to provide a process forseparating an asphalt-type bituminous material into a plurality offractions, each of which, because of the selectivity of separation ofthe process, possesses different physical and chemical properties.

These and other objects of the present invention will become moreapparent upon considering the following description of the presentinvention.

The present invention resides in the discovery that at least twofractions of an asphalt-type bituminous material may be obtained, one ofthem being in the liquid phase and the other being dissolved in thesolvent when a specific solvent is employed in certain volume ratios atspecific elevated temperature and pressure conditions. Since theinsoluble fraction may be separated from the asphalt-type bituminousmaterial in liquid phase and this separation occurs rapidly, the processlends itself to continuous operation. In accordance with the presentinvention, acetone when employed in certain volume ratios at specificelevated temperature and pressure conditions will accomplish the objectsand purposes of this invention.

The selection of the volume ratio of acetone to asphalt-type bituminousmaterial is, in accordance with the present invention, critical insofaras there is a minimum acetone to asphalt-type bituminous material volumeratio which is about 2:1. Where solvent to asphalttype bituminousmaterial volume ratios are less than 2:1, complete miscibility of thesolvent and asphalt-type bituminous material is obtained and separationof the bituminous material into its constituent fractions becomesimpossible. Increase of the volume ratio of acetone to asphalt-typebituminous material from about 2:1 to about 10:1 may increase, decreaseor leave unchanged the percent yield of asphaltenes depending on theasphaltictype material being treated and the temperature and pressurebeing used. As the volume ratio is increased above this latter value,the percentage yield does not appear to change significantly. Thus theselection of the volume ratio up to a value of 10:1 is determinative tosome extent of the percentage yield of asphaltenes obtained andconsequently offers measures for varying the properties of theasphaltene fractions. Using volume ratios above this latter value is ofno apparent operational advantage but does offer economic as well asoperational disadvantages.

In accordance with the present invention, I have discovered thetemperature employed must exceed 200 F. in order to obtain theseparation of a fraction which is in the liquid phase. In other words,it is necessary to operate at or above this temperature in order for abulk interface to form between the separated fraction and the acetonesolution of residual asphalt-type material. At temperatures below thislevel acetone causes the precipitation of a fraction, but this fractionis either semisolid or solid.

The maximum temperature of operation for the purpose of separating aliquid phase fraction comprising the total asphaltenes of theasphalt-type bituminous material treated is approximately 50 F. belowthe critical temperature of acetone. At values just above thistemperature, the density change of acetone is so rapid that not onlydoes an asphaltene fraction separate in liquid phase, but a portion ofthe resin content of the asphalttype bituminous material begins toseparate.

Selection of an operating temperature between 200 F. and about 50 F.below the critical temperature of the particular solvent employedprovides a convenient means for separating different fractions ofasphaltenes from the asphalt-type bituminous material. This is aparticularly important feature of the present invention since itprovides a method for obtaining different yields of asphaltenes from aparticular asphalt-type bituminous material. Variation in the yieldresults in fractions possessing different physical and chemicalproperties.

When operating within the aforesaid range of temperature for obtaining aliquid phase asphaltene fraction or a plurality of such fractions, it isof course essential that the pressure employed be not less than theequilibrium vapor pressure of acetone at its temperature. Higherpressures may, however, be employed. Utilization of these higherpressures, however, does not have any great effect upon the percentageyield of asphaltenes. In other words, the percentage yield is primarilya function of temperature.

Besides the fact that treatment of one volume of asphalt-type bituminousmaterial with at least two vol times of acetone at the stated elevatedtemperature and pressure conditions yields asphaltenes in the liquidphase, acetone is an excellent solvent for a number of other reasons.For example, the percentage yield of asphaltenes is fairly constant overa fairly wide temperature range, 100 or more degrees, and this permits afairly wide choice of operating conditions. Furthermore, when operatingwithin this wide temperature range, not only is an asphaltene fractionin the liquid phase obtained but the percentage yield is comparable tothat obtained when operating With n-pentane either at room temperatureand atmospheric pressure conditions or under the conditions described incopending application Serial Number 377, 201, filed August 28, 1953, nowabandoned. In addition, most of the known applications for asphaltcnesrequire a product having a softening point of 300 F. or above. Theasphaltene fraction obtained with acetone in accordance with the processof this invention 'has such a softening point. In this connection it issurprising that acetone will yield asphaltene fractions in the liquidphase having softening points of 300 F. or above while operating at atemperature, for example 225 F., considerably below the softening pointof the obtained fraction.

The residual or petrolene fraction dissolved in acetone may be separatedfrom acetone by flashing and thus produce a product having propertiesuseful, for example, in the paint, varnish and enamel industries. If,however, it is desirable to recover separate fractions of oils andresins, it is possible, in accordance with the present invention, toobtain such fractions by increasing the pre vailing temperatureconditions of the petrolene fraction dissolved in acetone.

In order to recover the resin fraction or a portion thereof from thepetrolenes in solution, it is simply necessary to increase thetemperature above 50 F. below the critical temperature of thehydrocarbon solvent while maintaining the pressure at a value at leastequal to the vapor pressure of acetone.

Surprisingly, the critical temperature (455 F.) of acetone is not themaximum temperature at which the resin fraction may be recovered in theliquid phase from the petrolenes in solution. As a matter of fact, Ihave discovered that temperatures appreciably in excess of the criticaltemperature of acetone may be employed for separating the resin fractionin the liquid phase from the petrolenes in solution while leaving theoils in solution, providing the pressure employed is of the-properchoice. The upper limit of operative temperature is that at 'whichdecomposition of acetone or the asphalt-type bituminous material beginsto take place.

In the case of operating below the critical temperature but within 50 F.thereof, the pressure employed must not be less than the vapor pressureof acetone at the temperature selected. In the case of temperatureconditions exceeding the critical temperature of acetone, the pressureemployed for a given temperature must not be less than the valueobtained by extrapolating the vapor pressure curve in accordance withthe Cox vapor pressure chart using Water as a reference substance.Extrapolation of the vapor pressure of acetone in accordance with theCox vapor pressure chart using water as a reference substance determinesthe minimum pressure that may be employed at a temperature above thecritical temperature of the solvent for obtaining the resins as a 5separate liquid phase from the petrolencs dissolved in acetone.

The construction of a Cox vapor pressure char-t using Water as areference substance is understood by those skilled in the art. Briefly,from a mathematical viewpoint, vapor pressure should be related totemperature as follows:

I T where P is the pressure, T is the boiling point and A log P and Bare constants. Cox found that if a constant is where T is the boilingpoint in degrees Fahrenheit at pressure P, and A and B are constants.

Now if we construct a vapor pressure curve for Water by plottingpressure as the ordinate on a logarithmic scale and temperature as theabscissa, a straight line vapor pressure curve may be obtained byselecting an arbitrary scale for the temperature values corresponding tospecific vapor pressures at these temperatures. Utilizing thetemperature scale arbitrarily selected for providing a straight linevapor pressure curve for Water, and using the same logarithmic scale forpressure values, Cox found that the vapor pressure curve of acetone,among other solvents, may also be plotted and that the resulting curveis a straight line. Values for plotting this straight line vaporpressure curve for acetone may be determined by known temperature-vaporpressure relationships at temperatures below the critical. This straightline may be extrapolated to temperatures beyond the critical temperatureof the solvent and the result is an extrapolation of the vapor pressurecurve in accordance with the Cox log P +B vapor pressure chart usingwater as a reference substance. An example of such extrapolation for anumber of solvents may be found in the sixth edition of the EngineeringData Book of the Natural Gasoline Supply Mens Association, Tulsa,Oklahoma, 1951. The particular chart occurring therein is a Cox vaporpressure chart constructed by Norman K. Rector.

By separating the resin fraction or a portion thereof by operation attemperature conditions above 50 F. below the'critical temperature and atpressure conditions hereinbefore defined, the resin fraction may bewithdrawn in the liquid phase from the separation zone leavingthe oilcontent or fraction of the asphalt-type bituminous material in solutionin acetone. A convenient means for recovering the oil from acetonesubsequent to the separation of the resin fraction is by simple flashingof the solvent followed, if necessary, by distillation to remove anyresidual solvent retained by the oil.

Prefer-ably, however, in accordance with the present invention, recoveryof the oil or any residual fraction such as a mixture of oils and resinsis obtained by maintaining the pressure of operation used in separatingthe".

separated solvent may be recovered by heat exchange against asolvent-rich'phase of any previous fraction resulting from the removalof constituents of the asphalttype bituminous material and may then beused in the process, for example, as feed to the first fractionatingstage where a high pressure solvent is required.

In copending application Serial No. 377,201, there is described aprocess scheme for continuous operation in the separation of anasphaltene fraction, a resin fraction, and oil fraction from anasphalt-type bituminous material employing certain selective hydrocarbonsolvents. The process scheme described there is equally applicable tothe present invention which employs acetone as a solvent. Specific datapresented hereinafter will illustrate the temperature and pressureconditions satisfactory for operating in accordance with this processingscheme when employing acetone as the solvent.

Although acetone is satisfactory for the purpose of the presentinvention, its homologue, methyl ethyl ketone, is not. Thus, when methylethyl ketone is used for the treatment of a 117 F. softening point, 87penetration at 77 F. asphalt at temperatures and pressures in accordancewith the present invention, there is no precipitation but instead acomplete solution of the entire asphalt sample. In other words, methylethyl ketone has too high a solvent power for such an asphalt. However,when treating highly blown asphalts, such as steep roofing blown asphalthaving a 195 F. softening point at elevated temperature and pressureconditions, the separation of asphaltenes is obtained in the liquidphase.

The following examples are for the purpose of illustration and are notlimiting to the scope of the present invention which is set forth in theclaims.

Example I The following tabulated data illustrates the separation of a117 F. softening point, 87 penetration of 77 F. vacuum-reduced asphaltinto an asphaltene fraction and a resin-oil fraction in accordance withthe method of the present invention when using acetone as the solvent.For the purpose of comparison, data is also included which illustratesthe separation of the same asphalt-type bitumi- In the case of employinga temperature of 75 F. and atmospheric pressure the asphaltene fractionseparated was in the solid state. However, when employing the recordedhigher temperature and pressure conditions, the separated asphaltenefraction was in the liquid state and was easily withdrawn from theequilibrium vessel.

Example II The resin-oil fraction of 69.6% by weight of the originalvacuum-reduced asphalt of Example I and having a softening point of 79F. is subjected to increased temperature and pressure conditions inorder to obtain a resin fraction in the liquid phase as follows:

Wt. Percent Press, of Resin Temp, F. p.s.i.g. (based on Remarksresin-oil wt.)

410 485 11 Solvent stable under equilibrium conditions. 470 800 20 Do.

After removal of the liquid resin phase, the oils are recovered fromsolvent solution by simple flashing.

Asphaltenc Fraction Resin-Oil Fraction Press, p.s.i.g.

Temp, F.

Yield, Soft. Pt., percent F.

Yield,

Soft. Pt., percent F.

Example IV The resin-oil fraction of Example III is subjected toincreased temperature and pressure conditions in order to obtain a resinfraction in the liquid phase as follows:

Wt. Percent Temp, F. Press, of Resin Remarks p.s.i.g. (based onresin-oil wt.)

460 777 9. 5 Slight decomposition of acetone.

What is claimed is:

l. A method of separating an asphalt-type bituminous material includingasphaltenes into at least two fractions, which method comprisesseparating a heavy fraction containing essentially asphaltenes from alighter solvent fraction containing dissolved residual asphalt-typebituminous material by treating in a single treating zone at elevatedtemperature and pressure each volume of the asphalttype bituminousmaterial with at least two volumes of a solvent consisting essentiallyof acetone, the temperature of treatment being between 200 F. and about400 F. and the pressure being at least equal to the vapor pressure ofthe solvent at the highest temperature present in the treating zone, theseparated heavy asphaltene fraction being in the liquid phase and havinga viscosity whereby it is freely flowable from the treating zone, andwithdrawing the liquid phase asphaltene fraction from the treating zone.

2. A method of separating an asphalt-type bituminous material includingasphaltenes into at least two fractions, which method comprisesseparating a heavy fraction containing essentially asphaltenes from alighter solvent fraction containing dissolved residual asphalt-typebituminous material by treating in a single treating zone at elevatedtemperature and pressure each volume of the asphalt-type bituminousmaterial with at least four volumes of a solvent consisting essentiallyof acetone, the temperature of treatment being between 200 F. and about400 F. and the pressure being at least equal to the vapor pressure ofthe solvent at the highest temperature present in the treating zone, theseparated heavy asphaltene fraction being in the liquid phase and havinga viscosity whereby it is freely flowable from the treating zone, andWithdrawing the liquid phase asphaltene fraction from the treating zone.

3. A method of separting an asphalt-type bituminous material includingasphaltenes into at least two fractions, which method comprisesseparating a heavy fraction containing essentially asphaltenes from alighter solvent fraction containing dissolved residual asphalt-typebituminous material by treating in a single treating zone at elevatedtemperature and pressure each volume of the asphalt-type bituminousmaterial with at least two volumes of a solvent consisting essentiallyof acetone, the temperature of treatment being between 200 F. and about400 F. and the pressure being at least equal to the vapor pressure ofthe solvent at the highest temperature present in the treating zone, theseparated heavy asphaltene fraction being in the liquid phase and havinga viscosity whereby 7 it is freely fiowable from the treating zone, andwithdrawing the liquid phase asphaltene fraction from the treating zone,the asphaltene fraction having a softening point of at least 300 F.

4. A method of separating an asphalt-type bituminous material includingasphaltenes into at least two fractions, which method comprisesseparating a heavy fraction containing essentially asphaltenes from alighter solvent fraction containing dissolved residual asphalt-typebituminous material by treating in a single treating zone at elevatedtemperature and pressure each volume of the asphalt-type bituminousmaterial with at least two volumes of a solvent consisting essentiallyof acetone, the temperature of treatment being between 200 F. and about400 F. and the pressure being at least equal to the vapor pressure ofthe solvent at the highest temperature present in the treating zone, theseparated heavy asphaltene fraction being in the liquid phase and havinga viscosity whereby it is freely fiowable from the treating zone,withdrawing the liquid phase asphaltene fraction from the treating zone,and then increasing the temperature of the lighter solvent fractioncontaining dissolved residual apshalt-type bituminous material to atemperature above the equilibrium temperature of the solvent at theprevailing pressure to separate the solvent.

5. A method of separating an asphalt-type bituminous material includingasphaltenes, resins and oils into at least two fractions, which methodcomprises separating a heavy fraction containing essentially asphaltenesfrom a lighter solvent fraction containing dissolved residualasphalt-type bituminous material by treating in a single treating zoneat elevated temperature and pressure each volume of the asphalt-typebituminous material with at least two volumes of a solvent consistingessentially of acetone, the temperature of treatment being between 200F. and about 400 F. and the pressure being at least equal to the vaporpressure of the solvent at the highest temperature present in thetreating zone, the separated heavy asphaltene fraction being in theliquid phase and having a viscosity whereby it is freely fiowable fromthe treating zone, withdrawing the liquid phase asphaltene fraction fromthe treating zone, separating a fraction of residual asphalt-typebituminous material from a lighter solvent fraction containing oils bytreating in a treating zone under further elevated temperature andpressure conditions the lighter solvent fraction containing dissolvedresidual asphalt-type bituminous material the temperature of thistreatment being greater than about 400 F. and the pressure attemperatures up to the critical temperature being at least equal to thevapor pressure of the solvent at the highest temperature present in thetreating zone, and at temperatures above the critical temperature thepressure being at least equal to the value obtained by extrapolating thevapor pressure curve of the solvent by a Cox vapor pressure chartextrapolation using water as the reference substance, the separatedfraction of residual asphalt-type bituminous material being in theliquid phase and having a viscosity whereby it is freely fiowable fromthe treating zone, and withdrawing the liquid phase fraction of residualasphalt-type bituminous material from the treating zone.

6. A method of separating an asphalt-type bituminous material includingasphaltenes, resins and oils into at least two fractions, which methodcomprises separating a heavy fraction containing essentially asphaltenesfrom a lighter solvent fraction containing dissolved residualasphalt-type bituminous material by treating in a single treating zoneat elevated temperature and pressure each volume of the asphalt-typebituminous material with at least four volumes of a solvent consistingessentially of acetone, the temperature of treatment being between 200F. and about 400 F. and the pressure being at least equal to the vaporpressure of the solvent at the highest temperature present in thetreating zone, the separated heavy asphaltene fraction being in theliquid phase and having a viscosity whereby it is freely fiowable fromthe treating zone, withdrawing the liquid phase asphaltene fraction fromthe treating zone, separating a fraction of residual asphalttypebituminous material from a lighter solvent fraction containing oils bytreating in. a treating zone under further elevated temperature andpressure conditions the lighter solvent fraction containing dissolvedresidual asphalt-type bituminous material, the temperature of thistreatment being greater than about 400 F. and the pressure attemperatures up to the critical temperature being at least equal to thevapor pressure of the solvent at the highest temperature present in thetreating zone, and at temperatures .above the critical temperature thepressure being at least equal to the value obtained by extrapolating thevapor pressure curve of the solvent by a Cox vapor pressure chartextrapolation using water as the reference substance, the separatedfraction of residual asphalt-type bituminous material being in theliquid phase and having a viscosity whereby it is freely fiowable fromthe treating zone, and withdrawing the liquid phase fraction of residualasphalt-type bituminous material from the treating zone.

7. A method of separating an asphalt-type bituminous material includingasphaltenes, resins and oils into at least two fractions, which methodcomprises separating a heavy fraction containing essentially asphaltenesfrom a lighter solvent fraction containing dissolved residualasphalt-type bituminous material by treating in a single treating zoneat elevated temperature and pressure each volume of the asphalt-typebituminous material with at least two volumes of a solvent consistingessentially of acetone, the temperature of treatment being between 200F. and about 400 F. and the pressure being at least equal to the vaporpressure of the solvent at the highest temperature present in thetreating zone, the separated heavy asphaltene fraction being in theliquid phase and having a viscosity whereby it is freely fiowable fromthe treating zone, withdrawing the liquid phase asphaltene fraction fromthe treating zone, the asphaltene fraction having a softening point ofat least 300 F., separating a fraction of residual asphalt-typebituminous material from a lighter solvent fraction containing oils bytreating in a treating zone under further elevated temperature andpressure conditions the lighter solvent fraction containing dissolvedresidual asphalt-type bituminous material, the temperature of thistreatment being greater than about 400 F. and

the pressure at temperatures up to the critical temperature being atleast equal to the vapor pressure of the solvent at the highesttemperature present in the treating zone, and at temperatures above thecritical temperature the pressure being at least equal to the valueobtained by extrapolating the vapor pressure curve of the solvent by aCox vapor pressure chart extrapolation using water as the referencesubstance, the separated fraction of residual asphalt-type bituminousmaterial being in the liquid phase and having a viscosity whereby it isfreely fiowable from the treating zone, and withdrawing the liquid phasefraction of residual asphalt-type bituminous material from the treatingzone.

8. A method of separating an asphalt-type bituminous material includingasphaltenes, resins and oils into at least two fractions, which methodcomprises separating a heavy fraction containing essentially asphaltenesfrom a lighter solvent fraction containing dissolved residualasphalt-type bituminous material by treating in a single treating zoneat elevated temperature and pressure each volume of the asphalt-typebituminous material with at least two volumes of a solvent consistingessentially of acetone, the temperature of treatment being between 200F. and about 400 F. and the pressure being at least equal to the vaporpressure of the solvent at the highest temperature present in thetreating zone, the separated heavy asphaltene fraction being in theliquid phase and having a viscosity whereby it is freely fiowable fromthe treating zone, withdrawing the liquid phase asphaltene fraction fromthe treating zone, separating a fraction of residual asphalt-typebituminous material from a lighter the pressure being at least equal tothe value obtained by 10 extrapolating the vapor pressure curve of thesolvent by a Cox vapor pressure chart extrapolation using water as thereference substance, the separated fraction of residual asphalt-typebituminous material being in the liquid phase and having a viscositywhereby it is freely flowable from the treating zone, Withdrawing theliquid phase fraction of residual asphalt-type bituminous material fromthe treating zone, and then increasing the temperature of the lightersolvent fraction containing oils to a temperature above the equilibriumtemperature of the solvent at the prevailing pressure to separate thesolvent.

References Cited in the file of this patent UNITED STATES PATENTS2,130,147 Milmore Sept. '13, 1938 2,276,155 Carr Mar. 10, 1942 2,337,448Carr Dec. 21, 1943

1. A METHOD OF SEPARATING AN ASPHALT-TYPE BITUMINOUS MATERIAL INCLUDINGASPHALTENES INTO AT LEAST TWO FRACTIONS, WHICH METHOD COMPRISESSEPARATING A HEAVY FRACTION CONTAINING ESSENTIALLY ASPHALTENES FROM ALIGHTER SOLVENT FRACTION CONTAINING DISSOLVED RESIDUAL ASPHALT-TYPEBITUMINOUS MATERIAL BY TREATING IN A SINGLE TREATING ZONE AT ELEVATEDTEMPERATURE AND PRESSURE EACH VOLUME OF THE ASPHALTTYPE BITUMINOUSMATERIAL WITH AT LEAST TWO VOLUMES OF A SOLVENT CONSISTING ESSENTIALLYOF ACETONE, THE TEMPERATURE OF TREATMENT BEING BETWEEN 200*F. AND ABOUT400*F. AND THE PRESSURE BEING BETWEEN 200*F. AND ABOUT 400*F. OF THESOLVENT AT THE HIGHEST TEMPERATURE PRESENT IN THE TREATING ZONE, THESEPARATED HEAVY ASPHALTENE FRACTION BEING IN THE LIQUID PHASE AND HAVINGA VISCOSITY WHEREBY IT IS FREELY FLOWABLE FROM THE TREATING ZONE, ANDWITHDRAWING THE LIQUID PHASE ASPHALTENE FRACTION FROM THE TREATING ZONE.